The invention relates to a hydraulic ram pump for converting low amounts of water at high pressure into large amounts of water at low pressure. Such ram pumps are also designated suction rams. Rams denote ram pumps which can be used in reverse for the conversion of large amounts of water at low pressure into low amounts of water at high pressure. The ram pump according to the invention can do both, that is to say it can optionally be used to increase pressure or to increase volume flow.
Suction rams have been known at least since 1905 ("Tragheitsmaschinen als Moglichkeit der hydraulisch-mechanischen Energieumformung" [Inertial machines as an option for hydraulic-mechanical energy conversion], presentation by Ivan Cyphelly, Fegawerk/Switzerland, held at the IHP of RWTH Aachen, Prof. Backe, Jun 21, 1991). They employ a ram valve which, as in the case of the hydraulic rams having a propulsion water pipe and a natural drop, is abruptly closed by the hydrodynamic pressure drop which is produced by the water flowing through the valve.
In the case of known suction rams (for example German Patent No. 804,288, 1949, or in the case of the suction ram still built today by the company Fegawerk S. A., Le Locie/Switzerland), when the ram valve closes the kinetic energy of the flowing water in the propulsion water line is dissipated, because the propulsion water is stopped. In order to keep this loss as small as possible, the suction ram from Fegawerk has as the propulsion water line a hose having an extremely large cross section, by which means high velocities of the propulsion water are additionally avoided.
The above-mentioned known suction rams require a specific constant propulsion water volume flow for satisfactory functioning, since when the propulsion water volume flow falls below that needed, the ram pump valve no longer closes and the efficiency falls to zero.
The ram valve is exposed to a particularly high loading as a result of the abrupt stopping of the propulsion water column, this loading being still considerably higher in known suction rams than in conventional hydraulic rams in which, as the result of the stopping of the propulsion water column, the pressure which is backed up at the valve is only that which must be achieved in order to deliver into an air receiver. This high loading on the ram pump valve has an unfavorable effect on the lifetime of the known suction ram.
These disadvantages are overcome by the ram pump described in the German Patent Application DE 19520343, which is not a prior publication (EPC Art. 54(3)), according to which the ram pump valve is not formed as a nonreturn valve, as in the previously mentioned prior art, which is held open by spring force and closed by the propulsion water flow, but as a valve which is held closed by spring force and opened by the propulsion water pressure.